Bulk Emergency key switch

[Daniel Jones]

Hi All,

Looking for some advice, I have been issued a drawing of a large warehouse lighting layout. the drawing shows 72 high bay lights including 29 self contained emergencies. The specification from the manufacture details that the Protective device must be a C16 and a maximum of 3 lights per MCB. I have managed to get the cable calculations to work. but its left me with a dilemma, I now have 24 circuits.

My plan was to wire 4 circuits through 6, 4 pole contactors. controlled by a number of switches (subject to what lights they would like on) located in the warehouse managers office. The issue i have is controlling the emergency switching.

There must be a way I can wire it so that I can have 1,2 or 3 key switches that will switch both the permanent and switch lines to each switched area to test the emergency.

trying to avoid having a bank of 24 key switches for each circuit.

any suggestions welcome.

Dan

 

[Timbo]

Use contactors to break the live feed to the emergency luminaires. Simple.

 

[Lucien Nunes]

You might be able to use smaller relays for the permanent feed, taking a line through the key switch to the PL relay and then through the normal switch to the SL contactor.

 

[Vortigern]

Get Channel LED emergency lights. They come with a remote version to test them. I mean a little remote control.
I presume the high bay are LED and 200-300 watts? If so, according to the IET COP for LED lights, there may be issues with inrush current that could cause melt-down of the contactors/switching. Just thought to bring that up as a heads up. Although I am surprised the manufacturers are saying only three to a 16A MCB. Oh and one final thought, how about sensors for switching?

 

[GBDamo]

Hi All,

Looking for some advice, I have been issued a drawing of a large warehouse lighting layout. the drawing shows 72 high bay lights including 29 self contained emergencies. The specification from the manufacture details that the Protective device must be a C16 and a maximum of 3 lights per MCB. I have managed to get the cable calculations to work. but its left me with a dilemma, I now have 24 circuits.

My plan was to wire 4 circuits through 6, 4 pole contactors. controlled by a number of switches (subject to what lights they would like on) located in the warehouse managers office. The issue i have is controlling the emergency switching.

There must be a way I can wire it so that I can have 1,2 or 3 key switches that will switch both the permanent and switch lines to each switched area to test the emergency.

trying to avoid having a bank of 24 key switches for each circuit.

any suggestions welcome.

Dan

I had a similar situation, 72 20w LED floods across 9 circuits, 9 circuits to meet MI inrush restraints.

At the time I was pondering the possibility of using time delay relays to reduce the number of circuits from 9 to 3. The customer liked the idea of 9 independently switched zones so I never pursued it.

My thinking was to put a 230V coil, time delayed relay after the first batch of lights and then set the relay for 2 seconds then this energises the next batch and so on until the circuit is effectively loaded.

Is there an off the shelf solution that performs this?

 

[Vortigern]

You can get surge limiters to obviate the problems of inrush currents @GBDamo
I also think you need to obtain the manufacturers charts detailing inrush current to devise the best strategy when designing your circuits. And yes there are staged switch on devices, often used in call centres to switch on the banks of computers in steps to limit problems of overload.

 

[GBDamo]

You can get surge limiters to obviate the problems of inrush currents @GBDamo
I also think you need to obtain the manufacturers charts detailing inrush current to devise the best strategy when designing your circuits. And yes there are staged switch on devices, often used in call centres to switch on the banks of computers in steps to limit problems of overload.

So how do these staged switches work?

Does it sit at the front of say five circuits and turn each on in sequence but is fed from one OCPD?

In this case it saves ways in the DB but still needs the circuits.

My idea would require far fewer circuits with the time delayed relays in line, may allow for a B type device and much longer circuits.

I'm obviously missing something?

 

[Vortigern]

I have only seen them in large offices, I suppose the expense might preclude them. You switch on maybe one hundred computers and they come on row by row taking about five minutes to switch on when used. I guess it is only used in such large ventures. I don't know of smaller versions, perhaps there are.

 

[GBDamo]

This is fueling my current ramblings so go easy...

 

[pc1966]

Sequential start is common for computer racks, etc. But for most LED lights the surge is only a cycle of 50Hz at most, so simple a bunch of relays (zero-crossing solid state if you like to be fancy) that turn on the 2nd lot when the first come on, etc, would do to stagger the switching.

Another option, though it flies in the face of the 3% VD rule, is to use a NTC surge suppressor. They have a few ohms R when cold and drop rapidly when hot, so limiting the initial in-rush.

Inrush current limiter - Wikipedia

en.wikipedia.org